With the recent advances in Internet content distribution, including peer-to-peer networks and real-time video streaming systems, in order to prevent unauthorized distribution of content, it becomes important to embed data in video to trace the point of distribution. The point of distribution is often an authorized viewer, such as a cinema where pirated copies are made with camcorders, or a set-top-box TV decoder whose output is captured and re-encoded into a video file. After tracing the source, measures can be taken to prevent further unauthorized distribution.
Embedding signals in video is a rich field both in academic research and commercial inventions. Covert watermarking in the compressed (MPEG) domain is well known in the art, as are overt watermarks that appear as bitmaps on top of the video, and steganographic watermarks.
Digital Watermarking of Visual Data: State of the Art and New Trends, by M. Barni, F. Bartolini and A. Piva., Congrès Signal processing X: Theories and Applications (Tampere, 4-8 Sep. 2000), EUPSICO 2000: European Signal Processing Conference No 10, Tampere, Finland (Apr. 9, 2000), briefly reviews the state of the art in digital watermarking of visual data. A communication perspective is adopted to identify the main issues in digital watermarking and to present the most common solutions adopted by the research community. The authors first consider the various approaches to watermark embedding and hiding. The communication channel is then taken into account, and the main research trends in attack modeling are overviewed. Particular attention is paid to watermark recovery due to the impact it has on the final reliability of the whole watermarking system.
Multichannel Watermarking of Color Images, by M. Barni, F. Bartolini and A. Piva., published in IEEE Transactions on Circuits and Systems for Video Technology, Vol. 12, No. 3, March 2002, describes that in the field of image watermarking, research has been mainly focused on grayscale image watermarking, whereas the extension to the color case is usually accomplished by marking the image luminance, or by processing each color channel separately. In this paper, a DCT domain watermarking technique expressly designed to exploit the peculiarities of color images is presented. The watermark is hidden within the data by modifying a subset of full-frame DCT coefficients of each color channel. Detection is based on a global correlation measure which is computed by taking into account the information conveyed by the three color channels as well as their interdependency. To ultimately decide whether or not the image contains the watermark, the correlation value is compared to a threshold. With respect to existing grayscale algorithms, a new approach to threshold selection is proposed, which permits reducing the probability of missed detection to a minimum, while ensuring a given false detection probability. Experimental results, as well as theoretical analysis, are presented to demonstrate the validity of the new approach with respect to algorithms operating on image luminance only.
Digital Watermarking for 3D Polygons using Multiresolution Wavelet Decomposition, by Satoshi Kanai, Hiroaki Date, and Takeshi Kishinami, available on the World Wide Web at citeseer.ist.psu.edu/504450.html, describes that recently much interest is being taken in methods to protect the copyright of digital data and preventing illegal duplication of it. However, in the area of CAD/CAM and CG, there are no effective ways to protect the copyright of 3D geometric models. As a first step to solve this problem, a new digital watermarking method for 3D polygonal models is introduced in this paper. Watermarking is one of the copyright protection methods where an invisible watermark is secretly embedded into the original data. The proposed watermarking method is based on wavelet transform (WT) and multiresolution representation (MRR) of the polygonal model. The watermark can be embedded in the large wavelet coefficient vectors at various resolution levels of the MRR. This makes the embedded watermark imperceptible and invariant to the affine transformation. And also makes the control of the geometric error caused by the watermarking reliable. First the requirements and features of the proposed watermarking method are discussed. Second the mathematical formulations of WT and MRR of the polygonal model are shown. Third the algorithm of embedding and extracting the watermark is proposed. Finally, the effectiveness of the proposed watermarking method is shown through several simulation results.
U.S. Pat. No. 7,068,809 of Stach describes a method wherein segmentation techniques are used in methods for embedding and detecting digital watermarks in multimedia signals, such as images, video and audio. A digital watermark embedder segments a media signal into arbitrary shaped regions based on a signal characteristic, such as a similarity measure, texture measure, shape measure or luminance or other color value extrema measure. The attributes of these regions are then used to adapt an auxiliary signal such that it is more effectively hidden in the media signal. In one example implementation, the segmentation process takes advantage of a human perceptibility model to group samples of a media signal into contiguous regions based on their similarities. Attributes of the region, such as its frequency characteristics, are then adapted to the frequency characteristics of a desired watermark signal. One embedding method adjusts a feature of the region to embed elements of an auxiliary signal, such as an error correction encoded message signal. The detecting method re-computes the segmentation, calculates the same features, and maps the feature values to symbols to reconstruct an estimate of the auxiliary signal. The auxiliary signal is then demodulated or decoded to recover the message using error correction decoding/demodulation operations.
U.S. Pat. No. 6,950,532 of Schumann et al. describes a visual copyright protection system, the visual copyright protection system including input content, a disruption processor, and output content. The disruption processor inserts disruptive content to the input content creating output content that impedes the ability of optical recording devices to make useful copies of output content.
The following references are also believed to reflect the present state of the art:
U.S. Pat. No. 6,760,463 to Rhoads;
U.S. Pat. No. 6,721,440 to Reed et al.; and
WO 02/07362 of Digimarc Corp.
The disclosures of all references mentioned above and throughout the present specification, as well as the disclosures of all references mentioned in those references, are hereby incorporated herein by reference.